1. Field of the Invention
This invention relates to a mask assembly and a method using the mask assembly for forming solder bodies on a substrate.
2. Description of the Related Art
As shown in FIG. 1, Taiwanese Publication No. 518919 discloses a solder paste printing method including: positioning a mask plate 11, which is formed with a plurality of through-holes 111, on a circuit board 12; filling the through-holes 111 with a solder paste 14 using a printing squeegee 13; and removing the maskplate 11 from the circuit board 12.
Because of industrial requirements, two or more different solder pastes (e.g., tin-zinc solder material, tin-copper solder material, etc.) are required to be printed on the circuit board 12. Although the method described above can be employed to form solder bodies on many regions of the circuit board 12, only one kind of solder paste (referred as a “first solder paste” hereinafter) can be printed thereon using the aforesaid procedure. If the other kind of solder paste (referred as a “second solder paste” hereinafter) is to be applied to the circuit board 12, on which the solder bodies of the first solder paste have been formed, using the aforesaid procedure with a second mask plate, the solder bodies of the first solder paste are likely to be damaged by the second mask plate. Therefore, the current procedure for applying a second solder paste to the circuit board cannot be conducted by the aforesaid printing techniques and can only be conducted by manually forming the solder bodies one at a time, thereby resulting in waste of time and manpower.
Therefore, there is a need in the art to provide a method and a mask assembly that can permit application of two different kinds of solder pastes to a substrate using a conventional printing apparatus.